In the typical vibration isolating hydraulic-elastomeric mount used for vehicle engines, there is normally a pair of elastomeric walled chambers which are divided by a rigid partition and are interconnected by an orifice either through or around such partition to produce a damping effect. However, such damping is not desirable under all circumstances. In the case of isolating and absorbing engine vibrations, it is desirable that there be little or no hydraulic damping at low amplitudes and frequency. To this end, there has evolved both a displaceable partition and a so-called "decoupler" member mounted for limited reciprocal movement thereon, both of which operate to effect cyclic volume change in the chambers at low frequencies and amplitudes without forcing liquid through the orifice and thus without the hydraulic damping. Examples of such hydraulic-elastomeric mounts representative of the present state of the art are disclosed in copending U.S. patent application Ser. No. 678,356, filed Dec. 5, 1984 which is a continuation-in-part of Ser. No. 461,612, filed Jan. 27, 1983, and Ser. No. 689,139, filed Jan. 7, 1985 which is a continuation-in-part of Ser. No. 554,526, filed Nov. 23, 1983 (now abandoned) and all assigned to the assignee of this invention. While such features have provided substantially improved engine vibration isolation and absorption, it has been found that improved road isolation for the engine and in particular reduced harshness on medium-to-hard impacts can be realized like in vehicle suspension shock absorbers and strut cartridges by also differentiating the hydraulic damping between jounce and rebound. In vehicle suspension shock absorbing devices the damping differentiation is normally provided by fine tuning a valve system so that there is less damping during wheel jounce than rebound.